In recent years, a number of services are available for delivering contents such as pictures or for sharing contents over the Internet. Among such services, some services have a single distributor providing contents of various genres; while some services are specialized in genres of expertise such as sports, news, music, movies, etc. It is anticipated that, in the future, such services will go on increasing. Besides, in addition to the Internet, services for providing high-quality pictures have also started over a closed IP network called NGN (Next Generation Network) that has bandwidth assurance. Thus, if the conventional broadcasting services such as terrestrial broadcasting services, BS broadcasting services, or CS broadcasting services are also taken into account; then the contents accessible to the users have explosively increased. Moreover, due to the increase in the capacity of memory devices and the decrease in the cost thereof; the local disks of AV devices, which reproduce pictures, have become capable of storing an enormous number of contents. Along with such diversification and ubiquitousness of services as well as with an explosive increase in the contents, it is becoming extremely difficult for the users to efficiently find out the intended contents. Given such a situation, a technology has been developed in which contents that are related to the selected contents are searched for in a local disk or over a network by referring to metadata of those contents, and then the display of contents is controlled (for example, JP-A No. 2008-227947 (KOKAI)).
However, in the technology disclosed in JP-A No. 2008-227947 (KOKAI), at the time of searching for contents over a network, there is a possibility that the contents cannot be retrieved depending on what type of services are available over the network. That is, as far as the search criteria such as acceptable search conditions, metadata formats, transmission protocols, searchable contents genres, or search formulae for searching contents or metadata; there can be a disparity between the services. Take the example of search conditions. It happens that a particular service allows a search by keywords only, but another service allows a search by keywords as well as a search by genres. Moreover, even among the services that allow a search by genres, it is often the case that the definitions of genres are not the same. Besides, it is often the case the services allowing a search by keywords implicitly point to full-text searching of metadata. However, there are some services which also allow a search by specification of titles, synopsis, keywords, or cast along with the specification of keywords. By taking into account such a variety among the services, if an inter-service search across a plurality of services is to be performed in a receiving apparatus that receives contents, the search formula for searching the intended contents needs to be incorporating the search criteria of all services. However, it is not an easy task to project, without any discrepancies, a search formula for searching the intended contents onto a search formula incorporating the search criteria of all services. Hence, when each of a plurality of services has different search criteria, the user may not be able to accurately search for the intended contents.